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That little orange 'shift up' light

Menzenski

Menzenski

Formerly Mambeu
Location
Home: Ithaca, NY School: Albuquerque, NM
I have a 1990 5spd Cherokee (base trim level). There's no tach, but there is a little orange arrow to the left of the guages that is lit up when I reach a certain rpm. Does anyone know what that rpm is? Knowing that would let me make a better estimate of the rpms.

On a somewhat related note, how difficult is it to install a tachometer in a vehicle that's never had one?

Thanks in advance.
 
It's easy - just get a 1987-1990 gage cluster, oil pressure sender, and coolant temperature sender (the senders are cheap, if you buy new.) Plan on two hours for the swap - and that's if I'm NOT in a hurry, or if I don't want to change the ODO to reflect the mileage of the vehicle that the gages are going into. That's the easiest way, and will give you the most bang for your buck.

For the "upshift" light, ignore it. It's there for "fuel economy" (yeah, right!) and has nothing to do with performance or driving. If it's bothersome, take it out.

As far as estimating shift RPM, go over to a buddy with the same engine and a tach, and listen to it run at, say, 2000/2500/3000/3500/4000 RPM, and you'll get a good idea what's going on. I shift more by ear than by tach anyhow - always have.

5-90
 
that light is worhtless. If I followed it's shift advice I'd be in 5th at 35MPH.
 
no, I have a tach and still have the shift light. It doesn't come on at any particular RPM, it is variable based on what the throttle position and load on the engine is. If I'm into it then the light doesn't come on until a higher RPM, if I'm grannying it then it comes on at about 2K RPM.
 
The light is actually part of the emissions, it is there to tell you when to shift for lower emissions. I ignore mine. As 87 stated it is not related to RPM, it seems to be related to Voo-Doo as far as I can tell.

Rev
 
Rev Den said:
The light is actually part of the emissions, it is there to tell you when to shift for lower emissions. I ignore mine. As 87 stated it is not related to RPM, it seems to be related to Voo-Doo as far as I can tell.

Rev
Click to expand...
Funny, I had thought voo-doo when trying to figure out that little light too. It certainly has no rhyme or reason on mine.
 
5-90 said:
or if I don't want to change the ODO to reflect the mileage of the vehicle that the gages are going into.
Click to expand...
How do you change the odometer? There's an '89 Wagoneer in my local pick-and-pull with full gauges, but it's got far fewer miles on it than my Cherokee.
 
You don't. Simply record the mileage on the old Odometer, and record the milelage on the new one, and make sure to disclose that to anyone you sell it to.

OR

You could go to a speedo shop and have it advanced.

Rev
 
Crack it open, and reset the dials. Takes patience, and good hands.

Failing that, you could chuck something into a drill motor and run it forward - just as long as you've got to GO forward. Going backwards requires tearing it to bits and putting it back together.

5-90
 
On the same note as the question about it being on jeeps with the tach; It is on jeeps with an automatic too, it just doesn't ever light up. So basically what I am saying is they used the same insrtument panel no mater what configuration you have. Look close and you can also see that you have an indicator for Part-Time 4wd and Full-Time 4wd but only Jeeps with the np241 actually had both part and full time 4wd. I am talking about a '97 - '01 but I am assuming it is the same for older models
 
I know they used different attached switches even if the wiring is all there. And, when I got my cluster, it had no bulbs for part or full time (must have been 2wd) so I added the part time bulb (stole it from check washer fluid's spot) and but not the upshift bulb.
 
That dumb little shift up light doesent actually come on a a set rpm.It uses calculated engine load and rpm. When the light comes on under light acceleration floor it and you will see what i mean......lmao ....seriously
 
Matthew Currie said:
No vacuum. It's controlled by the engine computer. Not that that matters, really, except to quibble. It's still worthless.
Click to expand...
Voo-Doo :D
 
I was test driving a '97 TJ today at work, used car, it had the tach and the upshift light. Just crusing it would come on at like 2200 rpm's, but when you were into it full throttle, it wouldnt come on unitll 4500 rpm's or so. Useless to have both IMO.
dunno.gif
 
Maybe it's different on earlier XJs than on my 97 5-spd, but I do find it handy when I'm not able to "watch" tach speed. Corner of the eye. I know pretty well that if I'm between gears, I've got enough torque to keep my current speed. And when 87 octane went over $3, I DID seem to pay a lil more attention to it.
 
'S funny - when I stopped listening to that light, my fuel mileage went UP. When I stopped using fifth gear/OD in my 88, it went up a little more!

I try to cruise right around 2800-3000RPM, per the tach, and that seems to net me right about 17MPG. When I replace the fuel metering sensors (HEGO, MAP, IAT,) I should shoot up around 20-22mpg (they're original, in an 88, with 250k miles on them!)

5-90
 
5-90 said:
'S funny - when I stopped listening to that light, my fuel mileage went UP. When I stopped using fifth gear/OD in my 88, it went up a little more!

I try to cruise right around 2800-3000RPM, per the tach, and that seems to net me right about 17MPG. When I replace the fuel metering sensors (HEGO, MAP, IAT,) I should shoot up around 20-22mpg (they're original, in an 88, with 250k miles on them!)

5-90
Click to expand...

Wow! That's exactly where I shift,... by ear. I remember I used to have an idiot shift light but can't remember for the life of me what happened to it or when it stopped working. That just shows you how much attention I paid to it.
 
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